Aburaki et al U.S. Pat. No. 4,406,899 discloses BMY-28142 in zwitterionic form and its acid addition salts (in zwitterionic form in injectable compositions). This amorphous zwitterionic form shows broader spectrum activity than ceftazidime and cefotaxime but may require special packaging and/or refrigeration.
Various crystalline acid addition salts of BMY-28142 are disclosed in U.S. Ser. No. 144,899 filed Jan. 19, 1988. These crystalline salts are the sulfuric, di-nitric, mono-hydrochloric, and di-hydrochloric acid salts and orthophosphoric acid addition salts (from 1.5 to 2 moles of orthophosphoric acid per mole of BMY-28142). These crystalline salts, while possessing better temperature stability in dry powder form than the amorphous zwitterion, require formulation with bases and/or buffering agents for aqueous constitution because they are too acidic for use either intramuscularly or intravenously. Combinations of various salts in either a lyophilized or precipitated form with BMY-28142 are disclosed in U.S. Ser. No. 001,945 filed Jan. 9, 1987 and/or G.B. Patent application No. 2,199,746A. These combinations are formed by lyophilization or cosolvent precipitation of an aqueous solution of the zwitterion of BMY-28142 and one or more salts in which said salts have sodium, lithium, calcium or magnesium cations and chloride, bromide or iodide anions. These combinations have improved temperature stability in dry powder form over the zwitterion in injectable form and while they provide, upon dilution, injectable concentrations at pH 3.5-7 without the need for any other buffering agents or bases, their stability is not as good as the crystalline salts.